EV Fundamentals: Plumbing System Architecture
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Plumbing System Architecture
03.08
| 00:00 | As we touched on earlier, the cooling systems in modern EVs are very complex, with the ability to transfer heat from one area to another, often to accomplish multiple goals at once. |
| 00:10 | The overarching reasoning behind this is that batteries are expensive and whatever can be done to reduce energy consumption is cheap in comparison to installing larger batteries. |
| 00:18 | Let's now look at what we want to achieve with the plumbing system. |
| 00:21 | First, we want to keep the battery cool. |
| 00:23 | We then also want the heat produced by the motor and inverter to serve a useful purpose. |
| 00:27 | And lastly, we also want to ensure that the onboard charger's heat can be used to warm the battery. |
| 00:33 | Once we've got an understanding of these requirements, we'll look at a few layouts for an EV conversion project that are simple enough to put together and that are going to accomplish most of these goals. |
| 00:41 | It's important to understand that the inverter and motor cooling loops can run at higher temperatures than the battery, so for high performance applications where the inverters and motors will be getting very hot, it's often best to keep this cooling system separate from the battery cooling system. |
| 00:55 | Secondly, the heat that's produced by the motor and inverter can be used by the occupants in the cabin for mild heating. |
| 01:01 | In cooler climates, often the heat created by the motor and inverter is all that's needed for primarily summer-driven cars, which is what most EV conversion vehicles often are. |
| 01:09 | Onboard chargers also require cooling, as does the battery while charging if the battery is too hot. |
| 01:14 | On the flip side, when batteries are cold, they need to be heated before they can charge. |
| 01:18 | Since an onboard charger requires water cooling, it makes sense to keep this charger in the same loop as the batteries. |
| 01:24 | It can warm up the coolant, and therefore the battery, when charging. |
| 01:27 | There are a lot of different coolant pumps available, but for the most part, plumbing systems use 3.25 inch or 19mm tubes and pumps. |
| 01:32 | Generally speaking, two pumps will be used, one for the battery and one for the motor and inverter loop. |
| 01:38 | With that said, if you're building a high power output vehicle, there's every chance you may need more pumps. |
| 01:43 | Most pumps can also be PWM-controlled, which stands for Pulse Width Modulation. |
| 01:47 | This allows them to run at different speeds, making the pump quieter and more efficient during normal operation. |
| 01:54 | When designing the plumbing system, it's crucial to always position the inlet of the pump directly after the coolant reservoir. |
| 02:00 | Otherwise, it's very difficult for the pump to self-prime, and there's a chance the system could develop airlocks, which are very hard to bleed. |
| 02:07 | Three-way valves can also be added to divert coolant. |
| 02:10 | So, for example, two options here could be to use a three-way valve on a heater core in the cabin, in the powertrain loop, to offer cabin heating, or use a three-way valve as a bypass that removes the radiator from the system for a battery. |
| 02:21 | This helps the battery warm up if it's really cold outside. |
| 02:25 | This now brings us to the end of the thermal section of the course, but before we finish up, let's quickly run over a few things that we've learned in this last module. |
| 02:32 | Inverter and motor cooling loops can run at temperatures substantially higher than the battery loop, so it's often best to keep them separate. |
| 02:38 | A good option to heating an EV system is to use the waste heat produced as efficiently as possible, where heat created by one component might then be used to warm up another. |
| 02:47 | Generally, two pumps will be used per car, though high-performance applications may require more. |
| 02:52 | Most pumps these days are PWM-controllable as well, meaning their speed can be altered depending on the needs of the system. |
| 02:59 | Lastly, three-way valves or multi-way valves are an extremely useful addition to an EV cooling system as you're able to divert coolant to suit the vehicle's changing requirements. |
